Thrombomodulin protects against lung damage created by high level of oxygen with large tidal volume mechanical ventilation in rats

Lung damage created by high tidal volume ventilation in rats with monocrotaline-induced pulmonary hypertension

Background

Rats with chronic hypoxia-induced non-inflammatory pulmonary hypertension (PH) are resistant to ventilator-induced lung injury. We investigated the effect of high tidal volume ventilation in another model of PH, monocrotaline (MCT)-induced PH, which is a type of inflammatory PH.

Methods

PH was induced in rats by subcutaneous injection with 60 mg/kg MCT. Normal control rats, rats at 2 weeks after MCT injection (MCT2), and rats at 3 weeks after MCT injection (MCT3) were ventilated with low tidal volume (LV, 6 mL/kg) or high tidal volume (HV, 35 mL/kg) for 2 h with room air without positive end-expiratory pressure. Arterial oxygen pressure (PaO₂) and Evans blue dye (EBD) extravasation were measured. Hypertensive pulmonary vascular remodeling was assessed morphometrically by the percentage of muscularized peripheral pulmonary arteries (%Muscularization) and the media wall thickness to external diameter ratio, namely percentage medial wall thickness (%MWT). To assess inflammation, lung IκB protein and cytokine mRNA expression levels were assessed.

Results

Baseline mean pulmonary arterial pressure was significantly higher in MCT rats (normal, 15.4 ± 0.5 mmHg; MCT2, 23.7 ± 0.9; and MCT3, 34.5 ± 1.5). After 2-h ventilation, PaO₂ was significantly lower in the HV groups compared with the LV groups in normal and MCT2 rats, but not in MCT3 rats. Impairment of oxygenation with HV was less in MCT3 rats compared with normal and MCT2 rats. Among the HV groups, MCT3 rats showed significantly lower levels of EBD extravasation than normal and MCT2 rats. HV significantly downregulated IκB protein expression in normal and MCT3 rats and increased IL-6, MCP-1, CXCL-1 (MIP-1), and IL-10 mRNA levels in MCT3 rats. %Muscularization, %MWT, and the expression of lung elastin were significantly higher in MCT3 rats than in normal and MCT2 rats.

Conclusion

We found that HV-associated damage might be reduced in MCT-induced PH rats compared with normal rats. The results of this and earlier studies suggest that hypertensive pulmonary vascular structural changes might be protective against the occurrence of ventilator-induced lung injury, irrespective of the etiology of PH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01867-6.

Upregulation of Fibrinogen-Like 1 Expression Contributes to Reducing the Progression of Preeclampsia

Fibrinogen-like 1 (FGL1) is involved in liver injury and liver regeneration, but its role in placenta and preeclampsia (PE) remains unclear. We assessed FGL1 expression in serum and placenta from L-NAME-induced PE-like mouse and in women with (n = 38) and without (n = 42) PE. For the mouse study, pregnant C57Bl/6 mouse (n = 6/group) were subcutaneously administered L-NAME with or without FGL1 once daily starting on days 7–14 of pregnancy and were sacrificed on gestational day (GD) 20. Maternal body weight, blood pressure, and urinary protein were assessed during GDs 8–20. The weight and length of the placenta and fetus were assessed. The placental structure was evaluated using hematoxylin staining. In the human study, the sera of the pregnant women during the late trimester were assessed with enzyme-linked immunosorbent assays (ELISAs). FGL1 expression in human trophoblast cell lines under L-NAME stimulation was measured using Western blotting and immunofluorescence staining. The detected FGL1 protein levels in serum and placenta were both significantly upregulated in patients and mouse with PE compared with those in the non-PE groups. FGL1 treatment decreased maternal hypertension and proteinuria, decreased fetal weight in mouse with PE, downregulated proinflammatory cytokine (interleukin-1b and interleukin-6) levels, and maintained the balance between antiangiogenic (fms-like tyrosine kinase-1) and proangiogenic (placental growth factor) substances in the placenta. L-NAME-upregulated FGL1 expression was inhibited following overexpression of FoxO3a. In summary, FoxO3a reduction is a potential pathophysiological mechanism leading to upregulated placental FGL1 expression that may play a pivotal role in preventing PE progression.

Protective Role of Recombinant Human Thrombomodulin in Diabetes Mellitus

Diabetes mellitus is a global threat to human health. The ultimate cause of diabetes mellitus is insufficient insulin production and secretion associated with reduced pancreatic β-cell mass. Apoptosis is an important and well-recognized mechanism of the progressive loss of functional β-cells. However, there are currently no available antiapoptotic drugs for diabetes mellitus. This study evaluated whether recombinant human thrombomodulin can inhibit β-cell apoptosis and improve glucose intolerance in a diabetes mouse model. A streptozotocin-induced diabetes mouse model was prepared and treated with thrombomodulin or saline three times per week for eight weeks. The glucose tolerance and apoptosis of β-cells were evaluated. Diabetic mice treated with recombinant human thrombomodulin showed significantly improved glucose tolerance, increased insulin secretion, decreased pancreatic islet areas of apoptotic β-cells, and enhanced proportion of regulatory T cells and tolerogenic dendritic cells in the spleen compared to counterpart diseased mice treated with saline. Non-diabetic mice showed no changes. This study shows that recombinant human thrombomodulin, a drug currently used to treat patients with coagulopathy in Japan, ameliorates glucose intolerance by protecting pancreatic islet β-cells from apoptosis and modulating the immune response in diabetic mice. This observation points to recombinant human thrombomodulin as a promising antiapoptotic drug for diabetes mellitus.

Recombinant human thrombomodulin attenuated sepsis severity in a non-surgical preterm mouse model

Neonatal sepsis is characterised by dysregulated immune responses. Lipid mediators (LMs) are involved in the regulation of inflammation. Human recombinant thrombomodulin (rhTM), an anticoagulant, has anti-inflammatory effects and might be useful for sepsis treatment. A stock caecal slurry (CS) solution was prepared from adult caeca. To induce sepsis, 1.5 mg/g of CS was administered intraperitoneally to 4 d-old wild-type FVB mouse pups. Saline (Veh-CS) or rhTM (3 or 10 mg/kg; rhTM3-CS or rhTM10-CS) was administered subcutaneously 6 h prior to sepsis induction, and liver LM profiles at 3 and 6 h post-sepsis induction and survival up to 7 days were examined. Mortality was significantly lower (47%) in the rhTM3-CS group and significantly higher (100%) in the rhTM10-CS group, compared with the Veh-CS group (79%, p < 0.05). Eleven LMs (12-HEPE, EPA, 14-HDHA, DHA, PD1, PGD₂, 15d-PGJ₂, 12S-HHT, lipoxin B₄, 12-HETE, AA) were significantly increased at 3 h, and five LMs (5-HEPE, 15-HEPE, 18-HEPE, 17-HDHA, PD1) were significantly increased at 6 h post-sepsis induction. Increased EPA, DHA, 12S-HHT, lipoxin B₄, and AA were significantly suppressed by rhTM pre-treatment. rhTM was protective against neonatal sepsis. This protective effect might be mediated via LM modulation. Further post-sepsis studies are needed to determine clinical plausibility.

Therapeutic potential of recombinant thrombomodulin for lung injury after pneumonectomy via inhibition of high-mobility group box 1 in mice

BACKGROUND

Surgical acute respiratory distress syndrome (ARDS) is an extremely critical condition which may occur after major lung resection. Despite advances in minimally invasive surgical procedures and progress in the therapeutic management of this disease, prognosis remains poor. In this study, we investigated the contribution of high-mobility group box 1 (HMGB1) in a surgical ARDS model and evaluated the possible therapeutic effect of recombinant thrombomodulin (rTM) for the treatment of surgical ARDS.

METHODS

C57BL/6J mice underwent left pneumonectomy. rTM was injected at 12 hours before surgery, followed by 12 hours for 3 days after surgery. Lipopolysaccharide (LPS) was administered at 2 hours after surgery. We conducted a histologic analysis and measured HMGB1, IL-6, IL-1β, and TNF-α in bronchoalveolar lavage fluid on day 3 after pneumonectomy. Data were compared between the treatment groups.

RESULTS

On histologic analysis, left pneumonectomy followed by LPS administration induced both severe inflammatory cellular infiltration and alveolar wall congestion with hemorrhage. rTM administration rescued these histologic changes. The level of HMGB1, IL-6, IL-1β, and TNF-α in bronchoalveolar lavage fluid was significantly increased by LPS administration after pneumonectomy and significantly decreased by rTM administration with LPS and pneumonectomy (p < 0.001). Also, LPS alone showed no statistical differences in HMGB1 or proinflammatory cytokine level compared with pneumonectomy (PNX) group. In addition, the survival outcome was also improved by rTM administration.

CONCLUSIONS

LPS administration after left pneumonectomy could induce the severe lung injury. PNX and LPS have similar contribution to this model and may play a synergistic role in this process. rTM may have the potential therapeutic effect for surgical ARDS via suppression of HMGB1 and the secretion of proinflammatory cytokines induced by the administration of LPS after left pneumonectomy.

Comparative Transcriptome Analysis Identifies CCDC80 as a Novel Gene Associated with Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a heterogeneous disorder associated with a progressive increase in pulmonary artery resistance and pressure. Although various therapies have been developed, the 5-year survival rate of PAH patients remains low. There is thus an important need to identify novel genes that are commonly dysregulated in PAH of various etiologies and could be used as biomarkers and/or therapeutic targets. In this study, we performed comparative transcriptome analysis of five mammalian PAH datasets downloaded from a public database. We identified 228 differentially expressed genes (DEGs) from a rat PAH model caused by inhibition of vascular endothelial growth factor receptor under hypoxic conditions, 379 DEGs from a mouse PAH model associated with systemic sclerosis, 850 DEGs from a mouse PAH model associated with schistosomiasis, 1598 DEGs from one cohort of human PAH patients, and 4260 DEGs from a second cohort of human PAH patients. Gene-by-gene comparison identified four genes that were differentially upregulated or downregulated in parallel in all five sets of DEGs. Expression of coiled-coil domain containing 80 (CCDC80) and anterior gradient two genes was significantly increased in the five datasets, whereas expression of SMAD family member six and granzyme A was significantly decreased. Weighted gene co-expression network analysis revealed a connection between CCDC80 and collagen type I alpha 1 (COL1A1) expression. To validate the function of CCDC80 in vivo, we knocked out ccdc80 in zebrafish using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system. In vivo imaging of zebrafish expressing a fluorescent protein in endothelial cells showed that ccdc80 deletion significantly increased the diameter of the ventral artery, a vessel supplying blood to the gills. We also demonstrated that expression of col1a1 and endothelin-1 mRNA was significantly decreased in the ccdc80-knockout zebrafish. Finally, we examined Ccdc80 immunoreactivity in a rat PAHmodel and found increased expression in the hypertrophied media and adventitia of the pre-acinar pulmonary arteries (PAs) and in the thickened intima, media, and adventitia of the obstructed intra-acinar PAs. These results suggest that increased expression of CCDC80 may be involved in the pathogenesis of PAH, potentially by modulating the expression of endothelin-1 and COL1A1.